Amorphous or microcrystalline aluminum-base alloys

ABSTRACT

The present invention relates to substantially amorphous or microcrystalline aluminium-base alloys. 
     Such alloys are of the following chemical composition: 
     
         Al.sub.a M.sub.b M&#39;.sub.c X.sub.d Y.sub.e 
    
     in which: 
     50≦a≦95 atom % 
     M representing one or more metals of the group Mn, Ni, Cu, Zr, Ti, V, Cr, Fe and Co with: 
     0≦b≦40 atom % 
     M&#39; representing Mo and/or W with: 
     0≦c≦15 atom % 
     X representing one or more elements of the group Ca, Li, Mg, Ge, Si and Zn, with: 
     0≦d≦20 atom % 
     Y representing the inevitable production impurities such as O, N, C, H, He, Ga, etc . . . , the proportion of which does not exceed 3 atom %. 
     The alloys according to the invention can be produced by means of known methods in the form of wires, strips, bands, sheets or powders in the amorphous or microcrystallized state, the grain size of which is less than 1000 nm, preferably 100 nm. They may be used either directly or as means for reinforcing other materials, or as surface coatings which are resistant to corrosion or wear.

The invention relates to substantially amorphous or microcrystallineAl-base alloys.

There are many alloys in an amorphous state, which are produced by rapidcooling at a rate which is generally higher than 10⁵ ° C./sec from arandom state (liquid or vapour). In particular, alloys of type T_(i)X_(j) are known, in which T represents one or more transition metals (inparticular iron) and X represents one or more metalloids (ornonmetalloids) such as B, P, Si, C, Al, and with i÷50 atom %. In suchalloys, Al occurs as a minor element, the proportion of which, generallyof the order of 10 atom %, does not exceed 35 atom %.

For Al-base alloys (containing more than 50 atom % Al), the technicalliterature reports on attempts to produce amorphous alloys, which werecarried out in relation to binary alloys containing Bi, Cd, Cu, Ge, In,Mg, Ni, Pd, Si, Cr, Ag or Zn, but only four of them, Al-Ge, Al-Pd,Al-Ni, Al-Cr were found to be very locally amorphous (regions which arevisible in electron microscopy), and that occurs with very high rates ofcooling of the order of 10⁹ to 10¹⁰ K./sec, which are very difficult toattain on an industrial scale: see T R ANANTHARAMAN et al `RapidlyQuenched Metals III`, volume 1, Editor B Cantor, The Metals Society,London (1978) page 126 and P FURRER and WARLIMONT, Mat Science and Eng,28 (1977) page 127.

With regard to ternary alloys, amorphous alloys were produced by A INOUEet al, (Journal of Mat Science 16, 1981, page 1895) but they relate tothe systems (Fe, Co, Ni)-Al-B, which may contain up to 60 atom % Al andgenerally from 15 to 45-50 atom % B.

The invention therefore concerns alloys based on Al, free from boron,which can be produced in a substantially amorphous or microcrystallinestate, by cooling at rates of the order of 10⁵ to 10⁶ K./sec, which canbe attained on an industrial scale, from a liquid or gaseous state.

The expression substantially amorphous alloy is used to denote a statein which the atoms are not in any order at a great distance,characterised by broad and diffuse X-ray diffraction spectra, withoutcharacteristic lines of the crystallised state; corresponding electronmicroscope investigations show that more than 80% by volume of the alloyis amorphous.

The expression microcrystalline state is used to denote an alloy inwhich 20% of the volume or more is in a crystallised state and in whichthe mean dimension of the crystallites is less than 1000 nm, preferablyless than 100 nm (1000 Å). Said mean dimension is evaluated from themid-height width of the line of the dense planes of the alloy, or byelectron microscopy (in the black field). In that state, the diffractionlines at low angles (θ<22°) have disappeared.

The microcrystalline alloys are generally produced either directly fromthe liquid state or by thermal crystallisation treatment above theinitial crystallisation temperature Tc of the amorphous alloy (that isdetermined hereinafter by differential enthalpic analysis, with aheating rate of 10° C./min). The alloys according to the invention havethe following chemical composition, defined by the formula:

    Al.sub.a M.sub.b M'.sub.c X.sub.d Y.sub.e

in which:

50≦a≦95 atom %

M representing one or more metals of the group Mn, Ni, Cu, Zr, Ti, V,Cr, Fe, and Co with

0≦b≦40 atom %

M' representing Mo and/or W with

0≦c≦15 atom %

X representing one or more elements of the group Ca, Li, Mg, Ge, Si, Znwith

0≦d≦20 atom %

Y representing the inevitable production impurities such as O, N, C, H,He, Ga, etc, the total proportion of which does not exceed 3 atom %, inparticular for the lightest elements, but which are preferably held at alevel below 1 atom %.

The proportion of additional elements is limited in an upward directionby virtue of metallurgical considerations (melting temperature,viscosity, surface tension, oxidisability, etc) but also inconsideration of economic factors (price and availability). The Mo and Ware limited to 15% as they substantially increase the density and themelting point of the alloy.

It has been found that it is easlier to produce a substantiallyamorphous or microcrystalline alloy if the proportion of Al is limitedin an upward direction to 85 atom %.

Substantially amorphous or microcrystalline alloys were produced withalloys containing between 6 and 25 atom % of Cu, with a value of 15≦b≦40atom %, with the level of impurities being held at less than 1 atom %.

Preferred compositions comprise individually or in combination, from 0.5to 5 atom % Mo, from 0.5 to 9 atom % Si, from 5 to 25 atom % V and 7 to25 atom % Ni.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings and Examples illustrate the invention.

FIG. 1 shows the X-ray diagram of an alloy Al₈₀ Cu₁₀ Ni₈ Mo₂, which isproduced by means of monochromatic radiation of Co (λ=0.17889 nm).

FIG. 1a shows the diagram of the amorphous alloy, FIG. 1b being a partof the FIG. 1a diagram on an enlarged scale.

FIG. 1c shows the diffraction diagram of the corresponding crystallisedalloy.

FIG. 2 shows the variation in hardness of the amorphous alloy accordingto the invention, versus time, when maintained at a temperature of 150°C.

EXAMPLE 1

Various alloys were poured in a helium atmoshere at 30 kPa (0.3 bar)from a liquid bath in a quartz crucible, on to the outside of a mildsteel drum with a diameter of 25 cm, rotating at a speed of 3000 rpm(V≃40 m/sec), so as to produce a strip measuring about 2 mm×20 μm incross-section.

The results of micro-hardess and/or X-ray study obtained thereon are setout in Table I below.

EXAMPLE 2

The alloy Al₈₀ Cu₁₀ Ni₈ Mo₂ produced above, which has a crystallisationtemperature Tc=156° C. and a density of 3.7 g/cm³, and with a ratio inrespect of electrical resistance in the amorphous state, relative toresistance in the crystallised state, at 300° K., of 7, was held at atemperature of 150° C.; FIG. 2 shows the variation in Vickersmicro-hardness, under 10 g, in that test: it reaches about 500 HV, after10 hours.

EXAMPLE 3

The alloy Al₇₂ Cu₁₅ V₁₀ Mo₁ Si₂ prepared as in Example 1 has acrystallisation temperature of 360° C. and a density of 3.6 g/cm³. Itsmicro-hardness reaches 750 HV after being held at 400° C. for half anhour and 840 HV after being held at 450° C. for half an hour.

The very high levels of hardness are advantageous with regard toproducing powders with a very high level of chemical homogeneity, bycrushing.

The alloys according to the invention may be produced using knownmethods, in the form of wires, strips, bands, sheets or powders in theamorphous state and/or in the microcrystallised state. They may be usedeither directly or as means for reinforcing other materials or they mayalso be used for producing surface coatings for enhancing corrosion orwear resistance.

                                      TABLE I                                     __________________________________________________________________________               POURING   VICKERS                                                             TEMPERATURE                                                                             MICROHARDNESS                                                                            STATE                                         COMPOSITION                                                                              (°C.)                                                                            UNDER 10 g X                                             __________________________________________________________________________    Al.sub.72 Cu.sub.15 V.sub.10 Mo.sub.1 Si.sub.2                                           1140      500        A                                             Al.sub.80 Cu.sub.9 Ni.sub.7 Mo.sub.1 Si.sub.3                                            850       400        A                                             Al.sub.75 Cu.sub.12 Ni.sub.10 Mo.sub.1 Si.sub.2                                          850       260        A                                             Al.sub.75 Cu.sub.11 Ni.sub.9 Mo.sub.2 Si.sub.3                                           850       220-410    A                                             Al.sub.70 Cu.sub.13 Ni.sub.11 Mo.sub.3 Si.sub.3                                          850       490        A                                             Al.sub.65 Cu.sub.16 Ni.sub.12 Mo.sub.3 Si.sub.4                                          850       410        A                                             Al.sub.80 Cu.sub.10 Ni.sub.8 Mo.sub.2                                                    850       310-360    A                                             Al.sub.60 Cu.sub.21 V.sub.14 Mo.sub.2 Si.sub.3                                           1300      --         A                                             Al.sub.77 Cu.sub.12 V.sub.8 Mo.sub.1 Si.sub.2                                            --        --         A                                             Al.sub.85 Cu.sub.8 V.sub.5 Mo.sub.1 Si.sub.1                                             --        --         A                                             Al.sub.80 Cu.sub.10 V.sub.7 Mo.sub.1 Si.sub.2                                            --        --         A                                             Al.sub.65 Cu.sub.18 V.sub.12 Mo.sub.2 Si.sub.3                                           --        --         m                                             Al.sub.72 Cu.sub.10 V.sub.14.5 Mo.sub.1 Si.sub.2.5                                       --        --         m                                             Al.sub.69 Cu.sub.17 Fe.sub.10 Mo.sub.1 Si.sub.3                                          --        --         m                                             Al.sub.72 Cu.sub.16.5 Fe.sub.8 Mo.sub.1 Si.sub.2.5                                       --        --         m                                             Al.sub.75 Cu.sub.14 Fe.sub.7 Mo.sub.1 Si.sub.3                                           --        --         m                                             Al.sub.78 Cu.sub.12 Fe.sub.6 Mo.sub.1 Si.sub.3                                           --        --         m                                             Al.sub.77 Cu.sub.12 Zr.sub.8 Mo.sub.1 Si.sub.2                                           1250      400        A - m                                         Al.sub.77 Cu.sub.12 Ti.sub.8 Mo.sub.1 Si.sub.2                                           1100      420        A - m                                         Al.sub.81 Cu.sub.12 Ni.sub.7                                                             850       --         A - m                                         Al.sub.80 Cu.sub.10 Ni.sub.8 Mo.sub.0.5 Si.sub.1.5                                       850       280        A - m                                         Al.sub.80 Mn.sub.18 Mo.sub.2                                                             960       550        m                                             Al.sub.85 Cu.sub.12 Si.sub.5                                                             850       --         m                                             Al.sub.83 Cu.sub.8 Ni.sub.4 Si.sub.5                                                     850       --         m                                             Al.sub.77 Cu.sub.11 Ni.sub.6 Si.sub.6                                                    850       250        m                                             Al.sub.78 Cu.sub.12 Mo.sub.2 Si.sub.8                                                    850       320        m                                             Al.sub.80 Cu.sub.10 Mn.sub.8 Mo.sub.2                                                    930       --         m                                             Al.sub.85 Cu.sub.7 Ni.sub.5 Mo.sub. 1 Si.sub.2                                           850       490        m                                             Al.sub.77 Cu.sub.12 Cr.sub.8 Mo.sub.1 Si.sub.2                                           850       540        m                                             Al.sub.77 Cu.sub.12 Mn.sub.8 Mo.sub.1 Si.sub.2                                           850       390        m                                             Al.sub.83 Cu.sub.17                                                                      800       --         m                                             Al.sub.75 Cu.sub.13 Ni.sub.10 Mo.sub.2                                                   930       --         m                                             Al.sub.97 Ni.sub.3                                                                       850       --         M                                             __________________________________________________________________________     X                                                                             A: amorphous  m: microcrystalline  M = macrocrystalline                  

We claim:
 1. A substantially amorphous or microcrystallized Al-basedalloy, said alloy being of the formula: Al_(a) M_(b) Cu_(b') M_(c'X)_(d) Y_(e), wherein a+b+b'+c+d+e=100 and 50≦a≦95 atom %, 15≦b≦40 atom %,6≦b'≦25 atom %, 0≦c≦15 atom %, 0≦d≦20 atom % and e≦1 atom %, and whereinM is an element selected from the group consisting of Mn, Ni, Zr, Cr,Ti, V, Fe and Co; M' is an element selected from the group consisting ofMo, W and mixtures thereof; X is an element selected from the groupconsisting of Ca, Li, Mg, Ge, Si and Zn; and Y represents the inevitablypresent impurities.
 2. The aluminum-based alloy of claim 1, whereinelement M' is Mo with the accompanying value of c being: 0.5≦c≦5 atom %.3. The aluminum-based alloy of claim 2, wherein element X is silicon andthe value of d is: 0.5≦d is ≦9 atom %.
 4. The aluminum-based alloy ofclaim 1, which is an amorphous alloy, wherein said element M is vanadiumwith the value of b ranging from 15≦b≦25 atom %.
 5. The aluminum-basedalloy of claim 1, which is an amorphous alloy, wherein element M isnickel having a b value ranging from 15≦b≦25 atom %.
 6. Thealuminum-based alloy of claim 1, wherein said alloy is amicrocrystallized alloy having a grain size less than about 1,000 nm. 7.The aluminum-based alloy of claim 6, wherein the grain size is about 100nm.